In the rigorous world of chemical research and development, the precise identification and confirmation of purity for synthesized compounds are paramount. 4-Chloro-1-naphthoic acid (CAS 1013-04-3), a compound of significant interest in organic synthesis and material science, is no exception. Understanding its spectroscopic characteristics is key to ensuring reliable experimental outcomes. NINGBO INNO PHARMCHEM CO.,LTD. provides this vital chemical intermediate, and here we explore its spectroscopic fingerprint.

The analytical characterization of 4-Chloro-1-naphthoic acid relies heavily on established spectroscopic techniques. Nuclear Magnetic Resonance (NMR) spectroscopy is a cornerstone for structural elucidation. Proton NMR (¹H NMR) typically reveals signals in the aromatic region (around 7.3–8.5 ppm) corresponding to the protons on the naphthalene ring. Crucially, the acidic proton of the carboxylic acid group appears at a much lower field, often around 12.5 ppm, providing a definitive marker. Carbon-13 NMR (¹³C NMR) further details the carbon environment, with the carbonyl carbon of the carboxylic acid group resonating at a distinct chemical shift, generally around 170 ppm, while aromatic carbons appear in the 120–140 ppm range. The presence of the chlorine atom influences these shifts, aiding in precise structural assignment.

Infrared (IR) spectroscopy offers complementary information about the functional groups present. The spectrum of 4-Chloro-1-naphthoic acid will characteristically display a broad O-H stretching band for the carboxylic acid dimer, typically in the 2500–3300 cm⁻¹ range. A strong carbonyl (C=O) stretching vibration, expected around 1700 cm⁻¹, confirms the presence of the carboxylic acid moiety. The C-Cl stretching vibration, though often weaker, appears in the fingerprint region below 800 cm⁻¹.

Mass Spectrometry (MS) is vital for determining the molecular weight and confirming the elemental composition. High-resolution mass spectrometry (HRMS) can provide a highly accurate mass measurement of the molecular ion, allowing for the unequivocal confirmation of the molecular formula, C₁₁H₇ClO₂. Fragmentation patterns observed in MS can also provide clues about the molecule's structure, such as the loss of hydroxyl or carboxyl groups.

For assessing the purity of 4-Chloro-1-naphthoic acid, High-Performance Liquid Chromatography (HPLC) is the method of choice. Typically employing a reversed-phase C18 column and a suitable mobile phase, HPLC can effectively separate the target compound from any synthesis byproducts or impurities. Detection is usually performed using UV-Vis spectroscopy, often at 254 nm, where the naphthalene ring system exhibits strong absorbance. Purity levels of ≥98% are often achieved and are critical for downstream applications.

The comprehensive spectroscopic analysis of 4-Chloro-1-naphthoic acid, from NMR and IR to MS and HPLC, provides researchers with the necessary confidence in their starting materials. This detailed analytical data, readily accessible through suppliers like NINGBO INNO PHARMCHEM CO.,LTD., underpins the reliability and reproducibility of synthetic processes and experimental investigations that utilize this important chemical intermediate.